The objective of this proposal is to provide early recognition and objective quantitation of response or progression of bone metastases in patients with prostatic carcinoma receiving hormonal therapy or chemotherapy. A variety of techniques will be applied to quantitate bone scintigraphy: 1) The activity of individual lesions on bone scans will be compared in the same patient on sequential scans done at three month intervals. The activity of Technetium-99m diphosphonate at these sites will be determined (see methods), stored, and compared on sequential scans; 2) the kinetics and distribution of Tc-99m-diphosphonate will be compared sequentially in the same patient and correlated with other measures of bone turnover in a short term metabolic study. These changes will be correlated with the details of patients' clinical courses. Ptients will be carefully evaluated on a standardized protocol to monitor disease response, stabilization or progression. Results of this quantitative scintigraphy and metabolic profile will be compared to response judged by both conventional reading of the scans and "digitalized" evaluation of the scans.